Tube closures warning

They say closing sections of track on Saturdays and Sundays rather than overnight is essential to preserve the weekday service and allow more engineering work to be completed.

However, they have not ruled out longer closures outside central London.

This weekend the Circle line and a major section of the District line will shut down.

And the Northern line's City branch will close its southbound line for three successive weekends from this weekend.

Both closures are for track replacement.

How to get the huge amount of heavy engineering work done as quickly as possible without causing serious disruption is now the most serious problem facing London Underground. Working at night is proving impractical, and overruns ruin the morning service.

The problem is worst on the deep lines. Heavy equipment has to be taken to the site for

12.30am then cleared by 4.30.

The two private- sector consortia, Metronet and Tube Lines, believe weekend closures are the best solution, although both have talked with LU about closing lines for weeks.

Tube Lines' spokesman said that although long-term closures had been discussed, "weekend closures would significantly improve what we need to do".

He added: " From an engineering point of view it makes a lot of sense. Obviously, LU has to balance that with what is best for their passengers."

Paul Emberley of Metronet said: "Productivity levels vastly increase during weekend closures. You can get much more value for money out of the time." Longer closures had been mooted "but are not really on the agenda".

An LU spokesman said: "The best time is to do it during weekend closures. We have not received formal proposals for longer-term closures from either Metronet or Tube Lines."

The Waterloo & City line may have to be closed for months. But it is different from the other lines in that it is only one and a half miles long and self-contained.

Ken Livingstone has effectively ruled out longterm closures of any other central London Tube line.

In doing so, the Mayor overruled Bob Kiley, his transport commissioner, who has said there may be a case for long-term closures of key sections. Business consortium London First said it would not necessarily be against long-term closures, subject to where these were to take place.

There would also need to be "cast-iron guarantees" that the work would be completed on time, it said.